{{! age 大于 20的学生显示？}}
{{#each student}}
 {{#if name}}
    {{#compare age 20}}
      <tr>
            <td>{{name}}</td>
            <td>{{transformat sex}}</td>
            <td>{{age}}</td>
          </tr>
    {{else}}
      <tr>
          <td>{{name}}</td>
          <td>{{transformat sex}}</td>
          <td>?</td>
      </tr>
    {{/compare}}
 {{/if}}
{{/each}}